could be alone in a crowded room|was alone with her thoughts|I want to be alone

source: wordnet30

3. lacking companions or companionship

he was alone when we met him|she is alone much of the time|the lone skier on the mountain|a lonely fisherman stood on a tuft of gravel|a lonely soul|a solitary traveler

source: wordnet30

4. exclusive of anyone or anything else

she alone believed him|cannot live by bread alone|I'll have this car and this car only

source: wordnet30

5. radically distinctive and without equal

he is alone in the field of microbiology|this theory is altogether alone in its penetration of the problem|Bach was unique in his handling of counterpoint|craftsmen whose skill is unequaled|unparalleled athletic ability|a breakdown of law unparalleled in our history

source: wordnet30

adverb

6. without any others being included or involved

was entirely to blame|a school devoted entirely to the needs of problem children|he works for Mr. Smith exclusively|did it solely for money|the burden of proof rests on the prosecution alone|a privilege granted only to him